The present invention relates to a window shade, and more particularly to an innovative structure of a light proof pleated window shade.
As shown in FIG. 1, a conventional pleated window shade 10 of prior art comprises a pleated blind 13 arranged between the upper rail 11 and the bottom rail 12. The pleated blind 13 is composed of a plurality of pleated portions, with each of pleated portions having a string hole 14 punched through both sides thereof for the purpose of accommodating therethrough a string 15. The string holes 14 are positioned in alignment. The upper rail 11 comprises a string pulley lock 16 located at the end portion thereof for controlling and restraining the movement of the string 15. The time-honored pleated window shade 10 described above is inherently defective in design in that its string holes 14 permit the light to pass through and can be used improperly as peep holes.
In order to overcome the problems mentioned above, the pleated window shade 20, as shown in FIG. 2, was introduced as exemplified in PCT WO 88/07345 in which the blind 21 of Y-shaped construction comprises the string holes 23 bring punched through the shoulders 22 thereof of a predetermined width extending outwardly in the same directed from the Y-shaped pleated portions of the blind 21. There is no doubt that the pleated window shade 20 as such can overcome the foregoing problems effectively. However, the pleated window shade 20 of prior art is disadvantageous in that it has never been produced in quantity economically and has been therefore marketed only on a trial basis, without the benefit of an enthusiastic reception by the consumers at large.
Another category of prior art structures is described by this inventor in the U.S. Pat. No. 5,054,534, in which this inventor discloses a pleated window shade comprising dual blinds. Needless to say, the cost of producing a pleated window shade with dual blinds, as proposed by this inventor, is inherently higher than that of producing a similar pleated window shade having a single blind. Therefore, an effort to improve the pleated window shade having dual blinds is called for.